A184-0009
Low Secondary Organic Aerosol Production from Oxygenated Volatile Chemical Products
Tuesday, 15 December 2020
Poster
Mackenzie Humes1, Mingyi Wang2, Sunhye Kim3, Jo Machesky4, Drew R Gentner4, Neil McPherson Donahue2 and Albert Presto1, (1)Carnegie Mellon University, Pittsburgh, PA, United States, (2)Carnegie Mellon University, Center for Atmospheric Particle Studies, Pittsburgh, PA, United States, (3)Carnegie Mellon University, Mechanical Engineering, Pittsburgh, PA, United States, (4)Yale University, Department of Chemical and Environmental Engineering, New Haven, CT, United States
Abstract:
Traditional anthropogenic Secondary Organic Aerosol (SOA) research has focused on various combustion sources, including emissions from factories, vehicles, and biomass burning. Emissions of Volatile Chemical Products (VCPs) and Intermediate Volatility Chemical Products (IVCPs) such as cleaning solvents, pesticides, coatings, and personal care products are now larger than emissions from more traditional sources, in part because of control measures on those sources and in part due to their near unity emission factors. Current models under-predict SOA formation and the oxidation products of I/VCPs are likely an overlooked source. These include various I/VCPs containing oxygen groups such as glycol ethers, esters, and oxygenated aromatics, whose SOA formation potential are poorly understood. I/VCPs containing oxygen groups may have a greater probability of undergoing fragmentation and inhibiting intramolecular hydrogen shifts when oxidized, resulting in less polar, lower molecular weight products. As the volatility is inversely dependent on molecular weight and polarity, the addition of these groups may prevent SOA formation. In this study, we observed the oxidation of common I/VCPs containing oxygen groups under high and low NOx conditions to determine their potential as SOA precursors.
We oxidized four glycol ether I/VCPs, two oxygenated aromatic VCPs, and two ester VCPs using an Oxidation Flow Reactor (OFR) at 50% RH with and without the presence of NOx. We measured SOA concentration and composition using an Aerosol Mass Spectrometer (AMS) and a Scanning Mobility Particle Sizer (SMPS) and gas phase I/VCPs and products using a Proton Transfer Reaction Mass Spectrometer (PTR-MS) and an iodide-adduct Chemical Ionization Mass Spectrometer (CIMS). All non-aromatic species had SOA yields of zero. The two aromatic ring-containing compounds: 2-phenoxyethanol and 1-phenoxy-2-propanol had SOA yields of approximately 15%. Iodide CIMS measurements confirm that products of non-aromatic oxygenated VCPs are too volatile to form SOA except under high aerosol loadings. This supports the idea that oxygen groups can inhibit SOA formation and that some oxygenated VCPs may be used in consumer products without making SOA.
